Apparatus for processing photographic films



Aug 13, DUGUID APPARATUS FOR PROCESSING PHOTOGRAPHIC FILMS Filed April 29, 1944 3 Sheets-Sheet l Inventor Roae'kz J D g 5y Aug. 13, 1946.

R. J. DUGUID APPARATUS FOR PROCESSING PHOTOGRAPHIC FILMS Filed April 29, 1944 3 Sheets-Sheet 2 0 w f\ V 41.4 5V fl Wa h .k V. 1T. 131 o wJ ,A #0. 0 0 .41 e 1F /l 7M MM Ray MM 1 Hui;

Aug. 13, 1946. R. J. DUGUID 2,405,645

APPARATUS FOR PROCESSING PHOTOGRAPHIG FILMS Filed April 29, 1944 a Sheets-Shet K .INVENTOR,

Rebel-t .-J0/17.2 Du guz d I Patented Aug. 13, 1946 APPARATUS FOR PROCESSING PHOTOGRAPHIC FILMS Robert John Duguid, Aberdeen, Scotland Application April 29, 1944, Serial No. 533,339

In Great Britain May 14, 1943 3 Claims.

This invention relates to apparatus for processing photographic films in comparatively long lengths such as cinematograph films or similar films employed for micro-copying or miniature camera work.

The invention is concerned with apparatus of the type in-which the film is traversed, in extended form, through a chamber or container within which the processing operation, which may be developing, fixing, washing, bleaching or other treatment, is efiected.

According to this invention an apparatus of the above type is provided with means for traversing the film first in a helical path proceeding in a direction from one side or end of the treatment chamber towards the other end and then in a helical path proceeding in the opposite, i. e. return, direction.

In the preferred form of'the invention the apparatus comprises an endless carrier surface, such as an endless band, belt or chain, which is arranged to be traversed in succession in two oppositely directed parallel helical paths and means for connecting the film to the carrier surface for movement therewith in the paths aforesaid.

is thereafter wound helically in the return direc-' tion around the top. and bottom rollers of the other pair. If desired, the apparatus may include a plurality of sets of rollers and an endless band which is wound in oppositely directed parallel helical paths over the rollers of each set in succession.

Another feature of the invention relates to the provision of a tensioning device through the intermediary of which the leading end of the film is adapted to be coupled to the endless carrier band and by means of which slack in the film which would otherwise occur during the windingon operation is avoided.

The foregoing and additional features of the invention are embodied in an apparatus which will now be described by way of example, with reference to the accompanying drawings in which- Figure 1 is a perspective view looking on the outside of the apparatus;

Figures 2 and 3 are perspective views at rightangles to each other showing the internal frame with its endless carrier and associated parts removed from the tank;

Figure 4 is a diagram showing the path of the endless carrier,

Figure 5 is a diagram, similar to Figure 4, but illustrating'a duplicated form of apparatus, employing four pairs of rollers.

Figure 6 is an enlarged fragmentary view showing means for coupling the conveyor belt to the film.

Like reference numerals indicate like parts throughout the figures.

Referring in the first place to Figures 1 to 4, the treatment chamber comprises a tank ll] of substantial depth within which is located an open rectangular framework It supporting rollers on which an endless carrier band I2 is mounted. There are two pairs of rollers l3, l4 and l5, l6, hereinafter referred to as the front pair and back pair respectively, all mounted for rotation about parallel horizontal axes extending from one side of the tank towards the other. The elements of each pair are positioned, as shown, one vertically above the other near the top and bottom of the tank respectively. The endless carrier band I2 is wound helically, from one side of the tank, around the top roller l4 and bottom roller l3 of the front pair, thus proceeding to the opposite side of the tank where the band is taken around the bottom roller R5 of the back pair and is then wound helically in the reverse direction around the rollers l5, it of the back pair, thus proceeding tothe original side of the tank where the band is taken over the top roller it of the front pair. The top rollers I l, N5 of the front and back pairs carry gear wheels l1, 18 .(Figure 4) with which a driving pinion I9 is in mesh. Th pinion i9 is adapted to be rotated selectively either by a hand crank 20 coupled directly to a spindle on which the pinion is mounted or through any suitable reduction gearing, indicated generally at 2|, from a small electric motor 22. The bottom rollers l3,- l5 of the two pairs are in the form of idlers which are driven by frictional contact with the endless band l2. tion of the two top rollers I l, l6 transmitted by the driving pinion l9, it will be appreciated that the endless band 12 will be traversed in a flat elongated helical path round the front rollers l3, l4 from one side of the tank to the other and then in a similar path round the back rollers l5,

On uni-directional rota- I! in the reverse direction across th tank. The direction of travel of the endless band over the rollers is indicated by arrowheads in Figure 4. The top and bottom rollers of both pairs are provided with annular guide fianges 23 adapted to separate adjacent .turns of the band. Alternatively for the same purpose guides might b provided on the fixed framework it which supports the rollers.

The roll of the film 50 to be treated, which may be on a spool, magazine or other container normally used in cameras, is mounted on or is held against the end of a shaft 24 located above and between the top rollers I4, 16. The shaft 24 is mounted on a bracket 25 supported on a top panel 28 of the framework. The shaft 2d engaging with the spool holding the film renders a braking action on the film as later described herein. The leading end 21 of the film is taken through a light-trapped opening 28 in the top panel 25, the position of the film being such that it may readily be connected to the endless band i2 as it passes from the top roller iii of the back pair to the top roller M of the front pair. The film is attached to the band by means of a collar 29 which is slidable on the band and is provided with a stop [2a so that the collar 29 if moved in one direction becomes fixed against the stop but is free to move in the opposite direction. Alternatively the band may be provided with a catch so arranged that when the collar is pulled in one direction, i. e.-in a direction opposed to that in which the band is travelling, the collar will grip the band, e. g. it may be arranged to engage holes or corrugations in the band. The leading end 2'! of the film is attached to the collar29 through the intermediary of a spring tensioning device 30, which may conveniently be a length of elastic material. One end of the tensioning device 301s attached to the collar 29 and the other end is either attached direct to the leading end of the film or to a second collar (not shown) which is slidable in either direction on the band and to which the leading end of the film is secured. As shown in Figure 6 the tensioning device 30 is provided at each end with a set of small hooks 30C to engage with the perforations in the film so that the ends of the film can be easily attached to the ends of the tensioning device 30. The device 30 may conveniently be composed, of an elastic part 30A and a part 30B attached to the collar 29, parts 30A and 303 being connected together by means of a. hook 39D attached to the part 30A and adapted to engage in a loop 29D fixed to the part 30B.

The shaft 24 on which the roll of film is mounted is provided with a spring brake (not shown) or like retarding device. When the top rollers l4, l6 are first set in motion this spring brake has the effect of ensuring that the tensioning device 30 will be extended to the maximum extent, after which the brake will slip and the film will be fed automatically to the top of the band. The length or strength of the tensioning device 30 is such that there is still a slight tensioning applied by it to the film when the latte has been fully wound on to the band.

It is to be appreciated that after a few turns of film have been wound on, the film is driven by frictional contact with the outer surface of the band 12 and owing to the different diameters involved the tendency is for the film to move faster than the band. If the leading end 27 of the film were connected directly to the securing collar 29, the slight difference in speed between the band and the film would result in the latter slackening of! near its attachment to the collar. The efiect of the tensioning device 30, by means of which the film is secured indirectly to the collar, is to take up the slack of the film as the winding proceeds.

The apparatus is operated in the following way. The film spool 50 is first mounted on its supporting shaft 24 which is uncovered by a .hinged lid 31 (mounted in the top panel 26 of the framework) which in the closed position, shown in Figure 1, forms a light-tight enclosure for the film so that the apparatus may be used for daylight loading. The leading end 21 of the film is attached, in the manner already described, to the band as it passes from the back top roller IE to the front top roller 14. The hinged lid 3| on the top panel is then closed thus sealing the light trap. The hand crank 29 is then rotated or the motor 22 set in motion until the film is fully wound on to the band. In order to indicate when the film has been fully wound on, the leading collar 29 may carry a projection arranged to operate a bell to give an audible warning. Alternatively, this projection may be arranged to raise a rod operating through the top panel 26, thus giving a visual signal that the winding-on process has been completed. Again, the arrangement may be such that the collar projection closes an electrical contact so as to illuminate a lamp. After the film has been fully wound on, as indicated by the foregoing signal, the trailing end of the film is attached to the band collar 29; thus the band is covered by the film with the tensioning device 30 between the two ends of the film. The desired processing operations may now be effected, the top rollers I 3, 46 either being driven by the hand crank 20 or by the motor 22. The tank i0 is provided at the top with a light-trapped inlet 32 for the treating solution and at the bottom with a cap-closed outlet or tap 33 through which the solution may be removed. Another inlet 5i may be provided in the top panel 26 or alternatively the panel inlet 5i may replace the tank inlet 32. It is only necessary to use a comparatively small quantity of the solution at the bottom of the tank, since in operation the film is continuously traversed under the bottom rollers I3, l5 of the two pairs on which the carrier band is mounted. After processing, one end of the film is secured to th film roll mounting shaft 24, or to a spool mounted thereon, and the film is rewound by rotation of the shaft 24 which, through the medium of a pinion 53 carried by the shaft, is

arranged for rotation by the hand crank 01' motor drive. The pinion 53 can be taken out of mesh with the driving pinion l9 when not required.

In the arrangment diagrammatically illustrated in Figure 5, the same principle of operation is entailed but an increased number of bandoarrying rollers are employed. The apparatus comprises four pairs of rollers 40 to 4'! arranged side by side in parallel pairs with the elements of each pair positioned one vertically above the other near the top and bottom of the tank respectively. The endless band I 2 is wound helically round the top and bottom rollers 40, 4| of the first pair, then helically in the reverse direction round the rollers 42, 43 of the second pair and so on round the top and bottom rollers 44, 45 of the third pair and top and bottom rollers 46, 4'! of the fourth pair, being carried from the top roller 46 of the last pair, over the top of the rollers, to the starting point of the first pair. The top rollers 42, 44 of the second and third pairs are directly driven by a main driving pinion l9, and the top rollers 40, 48 of the first and fourth pairs are driven through intermediate gear wheels 48.

The apparatus described above may be modified in many ways without departing from the essential features of the invention. For example, it will be appreciated that the size of the tank, the length of the endless carrier band and the number and length of'the band rollers may be varied in order to accommodate the apparatus to the processing of films of difierent lengths. For comparatively short length films such as those customarily used in so-called fminiature cameras, there may be but two convolutions of the endless 'band on each pair of rollers.

I claim:

1. Apparatus for processing photographic films in comparatively long lengths comprising a treat-.

ment chamber, means for traversing a film in extendedform through the treatment chamber,

said means comprising an endless carrier ar- I ranged to be traversed in succession in two op- 20 thereof.

for traversing a film in extended form through the treatment chamber, a coupling member for attaching a film to the band, a tensioning device in the form of a length of elastic material attached to said coupling member, and 'means for attaching opposite ends of the film to opposite ends of said tensioning device.

3. Apparatus according to claim 2 wherein said coupling member is free to move along the said band in the forward direction of movement ROBERT JOHN DUGUID. 

